Why can I no longer open pdf files in Photoshop or drag them into my files without completely locking up my system?

After updating to CC 2015, I am no longer able to drag pdf files into PS documents. When attempting to do so, it locks up PS and my system and I have to do a hard reboot because PS will not force quit. I've been dragging pdfs into PS docs for many years, so this is a new one on me.

If an application freezes, you can force quit that application - there should be no need for a system reboot.
Anything that freezes the full system and forces a reboot means it is happening at the OS level: an OS bug, a low level driver bug, or hardware failure. Applications cannot freeze the entire system.

So far you're the only one reporting that issue. It might be a bug, but why are other users not seeing it? So, we need to get more information about what is happening on your system to determine what is going on.